Unit 2: The Neuromuscular System

Question 1

How many muscles are there in the body?

Answer 1

Over 600, making up 40% of a person’s total weight

Question 2

What’s another name for bones & joints in the body framework?

Answer 2

Levers (bones)

Pivots (joints)

Question 3

What are the 3 types if muscle tissue, their control, appearance & location?

Answer 3

• Cardiac muscle (Autonomic nervous system) (myocardium) - striped - the heart
• contraction of the heart is controlled by the SAN (Sinoatrial node)
• Smooth muscle (Autonomic) - Smooth, spindle shaped - the walls of the small intestine
• Skeletal muscle (somatic nervous system) - striped - the hamstrings or triceps

Question 4

What are the 4 key characteristics of muscle tissue?

Answer 4

• Contractility (ability to shorten)
• Extensibility (ability to stretch & lengthen)
• Elasticity (ability to return to its original size & shape)
• Excitability (ability to respond to stimuli from the nervous system.

Question 5

What are the two types of skeletal muscle fibres & their key structural & functional features as well as examples of activities

Answer 5

• Slow twitch (type 1)
  Structural fts: small diameter - larger myoglobin content - many mitochondria - many capillaries to deliver blood & oxygen - red in colour

Functional fts: increased oxygen delivery - produces less force - long term contractions - resistance to fatigue - aerobic

Activities: maintaining posture - endurance based activities - lower intensity aerobic activities

• Fast twitch (type 2) - larger diameter - smaller myoglobin content - fewer mitochondria - fewer capillaries - white in colour

Functional fts: decreased oxygen delivery - generates more force - short term contractions - less resistant to fatigue - anaerobic

Activities: rapid, intense movements - strength training - sprinting - anaerobic training

Question 6

Exercise & type if training undertaken also affect muscle fibre proportions. Name 2 effects of exercise on muscle fibres?

Answer 6

• Intense exercise that brings about anaerobic metabolism will boost muscular strength & mass, and increase the size of fast twitch fibres.
• Moderate-intensity, aerobic endurance exercise that increase the volume of blood & oxygen to the muscle will develop the aerobic capacity of slow twitch fibres

Question 7

What is the name of the fibre that can adapt in different ways depending on he type of training performed

Answer 7

Intermediate fibres

Question 8

How do skeletal muscles create movement?

Answer 8

• muscles receive message from the brain to shorten
• muscles exert a force & pull on the bones
• as one muscle contacts & shortens, it works in pairs with an opposing muscle, which relaxes and lengthens

Question 9

What is an origin?

Answer 9

The start point of a muscle with is the attachment site on the bone that serves as a relatively fixed, motionless anchor point.
It is described as the proximal attachment, one nearest to the centre midline of the body.

Question 10

What is an Insertion?

Answer 10

The end of the muscle attached to the bone that usually moves during contraction. The insertion is described as the distal attachment, the one furthest away from the centre midline. Muscles usually have a single insertion.

Question 11

What is the name for muscles that move under tension by either lengthing & shortening and the two terms?

Answer 11

Isotonic:
Concentric contraction - the muscle shortens under tension. I.e the insertion moves towards the origin e.g the curling/ upward phase of the bicep curl

Eccentric contraction - the muscle lengthens under tension I.e the insertion moves away from the origin e.g the straightening/downward phase of the bicep curl

Question 12

What is the name given when muscles remain the same length under tension?
Give an example

Answer 12

Isometric

E.g holding a squat at the bottom of the movement

Question 13

What are the 4 roles of different muscles during movement?

Answer 13

Agonist/ prime mover - the muscles that contract & causes a desired action e.g the bicep brachii contracts during a bicep curl or the quadriceps during a leg extension

Antagonist - the opposing muscle to the agonist that is relatively relaxed e.g the triceps brachii during a bicep curl or the hamstrings during a leg extension

Synergist - the muscles that contract to assist or modify the movement of the prime mover e.g during hip extension the hamstrings act as Synergists for the gluets

Fixators - the muscles that contract to stabilise the part of the body that remains fixed e.g the shoulder griddle muscles stabilise the Scapula to allow for efficient move by at the shoulder joint when the arm moves.

Question 14

What is the main role of the nervous system?

Answer 14

To maintain a constant balance of the internal environment known as homeostasis. It achieves this with help from the brain. And a huge, complex network of electrical nerves and chemical messages that run throughout the body.

Question 15

What is the 3 nervous system functions?

Answer 15

1- Gather information (Sensation)
2- Analyse the gathered information (Integration)
3- Respond appropriately to the information (Response)

Question 16

What are the 4 receptors within the sensation phase of the nervous system?

Answer 16

Baroreceptors - detect changes in blood pressure

Proprioceptors - detect changes in muscle length & tension

Chemoreceptors - detect changes in chemicals e.g taste, smell

Thermoreceptors - detect changes in temperature

Question 17

What are the 2 primary divisions in the nervous system?

Answer 17

• Central Nervous System (CNS) - The Brain & Spinal Cord - the control base for the whole Nervous System. All nerve impulses that stimulate muscles to contract and create movement of the body orginate from the CNS.
• Peripheral Nervous System (PNS) - consists of all the branches of nerves that lie outside of the spinal cord. It’s role is to transport messages through its network of nerve cells, to & from the CNS.

Question 18

The Peripheral Nervous System (PNS) is split into 2 categories. What are they?

Answer 18

• Somatic system - controls voluntary (conscious) movement of the skeletal muscles e.g standing, walking & lifting weight
• Autonomic system - controls involuntary functions e.g digestion & heart ratw

Question 19

What are Neurons (nerve cells) responsibile for?

Answer 19

Transmitting electricial messages

Question 20

What are the 2 types of spinal nerves?

Answer 20

• Sensory neurons - carry messages from the sensory organs - arrive on the posterior side of the spinal cord from variety of sensory receptors.
• Motor neurons - transmit impulses from the CNS to muscles and glands with specific instructions, such as causing muscles to contract & glands to secrete hormones. These exit in the anterior side if the spinal cord

Question 21

Describe the structure of a neuron

Answer 21

• Cell body (directs the activities of the neuron)
• Nucleus (stores the cells genetic info. Tells it what to do)
• Dendrite (pick up impulses & transmit these to the body)
• Axon (transmits messages away from the cell body)
• Myelin Sheath (insulates the axon to speed up transport of messages)

Question 22

What is a motor unit recruitment and the all or none law?

Answer 22

A motor unit consists of a single motor neuron and all the muscle fibres it innervates (activates).
A single motor neuron may be responsible for in berating thousands of muscle fibres depending on its location and function. This is known as the innervation ratio.

When an impulse is sent down a neuron, all the muscle fibres within that motor unit are innervated. The motor unit activates ALL of its fibres OR NONE at all

Question 23

A motor unit is typically make up of one type of muscle fibre (slow or fast twitch) spread throughout the muscle. What’s the difference?

Answer 23

• Tasks requiring less effort, smaller neurons controllung slow twitch fibres are recruited
• Tasks requiring more effort, larger neurons controlling fast twitch fibres are recruited

Question 24

Name the 3 different neuromuscular sensory organs

Answer 24

Joint receptors - they are found in the ligaments and joint capsule. They inform the brain about the position of the joint.

Muscle spindles - are found in the muscle belly and inform the brain about the length of a surrounding muscle fibre. This helps to prevent overstretching & resultant damage.

Golgi tendon organs (GTOs) - found in the tendons & tell the brain how much tension a muscle is under.

Question 25

What are the short term effects of exercise on the neuromuscular system?

Answer 25

• increased muscle temperature
• increased muscle pliability (ability to stretch)
• Increased power output from muscles
• Increased nerve to muscle link
• Increased recruitment of muscle fibres

Question 26

What are the long term benefits of exercise on the neuromuscular system?

Answer 26

• increased muscular endurance/ hypertrophy/ strength
• Increased storage of glycogen & creatine phosphate in muscles
• Increase in contractile proteins, actin & myosin
• Increased basal metabolic rate
• Improved posture
• Increase in the size & numbers of capillaries surrounding muscle fibres
• Increased neuromuscular connections
• Increased recruitment of motor units

Question 27

What are the 4 parts of the brain?

Answer 27

• Cerebrum - largest & most superior aspect
• Cerebellum - The smaller part; it is inferior to the cerebrum & posterior to the brain stem. Acts as a memory bank. Mainly responsible for controlling the group action of muscles.
• Diencephalon - Thalamus & hypothalamus
• Brain Stem - the stalk like component at the inferior aspect of the brain. Lower portion is a continuation of the spinal cord.